Singh was greeted by officials and journalists accompanying him on his visit to the US.
Among others who wished the Prime Minister on his birthday were Gujarat Chief Minister and BJP's Prime Ministerial candidate Narendra Modi and Tamil Nadu Chief minister J Jayalalithaa.
"Best wishes to Prime Minister Manmohan Singh on his birthday. I pray for his long and healthy life ahead," Modi wrote on microblogging site Twitter.
In her message to Singh, Jayalalithaa said, "On the joyous occasion of your birthday, I would like to convey my warm felicitations to you and wish you many more happy returns of the day.
Born in 1932 in Gah Begal village in what is now Punjab province of present-day Pakistan, Singh's family shifted to India during partition.